Garlic (Alliium sativun L.) and its related preparations are included in the United States Pharmacopoeia and European Pharmacopoeia. Alliin and allicin are confirmed as the major active ingredients. But the content of alliin or allicin in garlic preparations in the market at home and abroad is very low. Research and development of new garlic preparations with safety, effectiveness and controllable quality has attracted more and more attention among researchers around the world.
1. Alliin
Chemical name: S-Allyl-L-cysteine sulfoxide
Melt point: 163-165° C. (decompose and carbonize)
Specific rotation: [α]D=+60°
White crystalline powder, and almost odorless.
Structure:

Molecular Weight: 177.22.
Patents cited: In a method of extracting alliin from fresh garlic (ZL 001012444) and a producing process for extracting alliin from fresh garlic (ZL 03100420.2), garlic which is in compliance with the garlic monograph in Pharmacopoeia is peeled and washed with pure water, then subjected to inactivation of alliinase under microwave radiation for 5-10 minutes or by boiling with boiling water for 5-10 minutes. The inactivated garlic is pulped, extracted with pure water or 5-70% alcohol, concentrated, filtered, absorbed with ion exchange column chromatography, eluted with ammonia, concentrated, and dried by spray-drying, and then the alliin as pharmaceutical raw material is obtained by recrystallization. Alliin content: ≧90%, according to HPLC analysis.
2. Alliinase (EC 4.4.1.4)
Synonym: Alliin lyase, S-allyl-L-cysteine sulfoxide lyase
Alliinase is a glycoprotein dipolymer, where the molecular weight of the two subunits is 51.5 KDa. It is a yellowish crystal, odorless, and the isoelectric point is 4.9.
Patents cited: In a producing process for extracting alliinase from fresh garlic (ZL 03100419.9), garlic which is in compliance with the garlic monograph in Pharmacopoeia is peeled and washed with pure water. The peeled garlic is pulped with colloid mill and alliinase is extracted therefrom with a protective buffer solution. After precipitation of alliinase with (NH4)2SO4 or PEG-4000˜8000, the precipitation is collected with a continuous low-temperature tube centrifuge. Then the precipitation is again dissolved in the protective buffer solution. After removal of the macromolecule and micromolecule substances with two sets of ultrafiltration devices, respectively, the buffer solution is subjected to lyophillization to obtain alliinase as pharmacal raw material. The enzyme activity of alliinase is ≧1000 IU/g determined by HPLC with alliin as substrate.
3. Allicin
Chemical name: thio-2-propene-1-sulfinic acid S-allyl ester
Density: 1.112 g/cm3 
Melt point: 25° C. (decompose)
Molecular weight: 162.3
Allicin is faint yellow volatile viscous liquid at room temperature, slightly soluble in water, and with strong odour. Allicin decomposes and deteriorates within a few hours when exposed to air.
One Allicin molecule is formed by catalytic decomposition of two alliin molecules by alliinase, i.e., 354.4 g alliin (2[C6H11NO3S]=2×177.2=354) can form 162.3 g Allicin ([C6H10OS2]=162). The yield is about 90%. The production can be calculated as follows:Production of allicin=mass of alliin×C×(162.2/354.4)×0.9
where C represents purity of alliin added, and 0.9 represents the reaction coefficient.
Reaction formula is as follows:
